Buggy code:
public class GenericConversionService implements ConversionService , ConverterRegistry { private static final GenericConverter NO_OP_CONVERTER = new GenericConverter ( ) { public Set < ConvertiblePair > getConvertibleTypes ( ) { } public Object convert ( Object source , TypeDescriptor sourceType , TypeDescriptor targetType ) { return source ; } public String toString ( ) { } } ; private static final GenericConverter NO_MATCH = new GenericConverter ( ) { public Set < ConvertiblePair > getConvertibleTypes ( ) { } public Object convert ( Object source , TypeDescriptor sourceType , TypeDescriptor targetType ) { throw new UnsupportedOperationException ( ) ; } public String toString ( ) { } } ; private static final Log logger = LogFactory . getLog ( GenericConversionService . class ) ; private final Map < Class < ? > , Map < Class < ? > , GenericConversionService . MatchableConverters > > converters = new HashMap < Class < ? > , Map < Class < ? > , GenericConversionService . MatchableConverters > > ( 36 ) ; private final Map < GenericConversionService . ConverterCacheKey , GenericConverter > converterCache = new ConcurrentHashMap < GenericConversionService . ConverterCacheKey , GenericConverter > ( ) ; public void addConverter ( Converter < ? , ? > converter ) { } public void addConverterFactory ( ConverterFactory < ? , ? > converterFactory ) { } public void addConverter ( GenericConverter converter ) { } public void removeConvertible ( Class < ? > sourceType , Class < ? > targetType ) { } public boolean canConvert ( Class < ? > sourceType , Class < ? > targetType ) { } @ SuppressWarnings ( "unchecked" ) public < T > T convert ( Object source , Class < T > targetType ) { } public boolean canConvert ( TypeDescriptor sourceType , TypeDescriptor targetType ) { } public Object convert ( Object source , TypeDescriptor sourceType , TypeDescriptor targetType ) { assertNotNull ( sourceType , targetType ) ; if ( GenericConversionService . logger . isDebugEnabled ( ) ) { GenericConversionService . logger . debug ( ( ( ( ( ( "Converting<seq2seq4repair_space>value<seq2seq4repair_space>" + ( StylerUtils . style ( source ) ) ) + "<seq2seq4repair_space>of<seq2seq4repair_space>" ) + sourceType ) + "<seq2seq4repair_space>to<seq2seq4repair_space>" ) + targetType ) ) ; } if ( sourceType == ( TypeDescriptor . NULL ) ) { Assert . isTrue ( ( source == null ) , "The<seq2seq4repair_space>value<seq2seq4repair_space>must<seq2seq4repair_space>be<seq2seq4repair_space>null<seq2seq4repair_space>if<seq2seq4repair_space>sourceType<seq2seq4repair_space>==<seq2seq4repair_space>TypeDescriptor.NULL" ) ; Object result = convertNullSource ( sourceType , targetType ) ; if ( GenericConversionService . logger . isDebugEnabled ( ) ) { GenericConversionService . logger . debug ( ( "Converted<seq2seq4repair_space>to<seq2seq4repair_space>" + ( StylerUtils . style ( result ) ) ) ) ; } return result ; } if ( targetType == ( TypeDescriptor . NULL ) ) { GenericConversionService . logger . debug ( "Converted<seq2seq4repair_space>to<seq2seq4repair_space>null" ) ; return null ; } Assert . isTrue ( ( ( source == null ) || ( sourceType . getObjectType ( ) . isInstance ( source ) ) ) ) ; GenericConverter converter = getConverter ( sourceType , targetType ) ; if ( converter == null ) { <START_BUG> if ( ( source == null ) || ( targetType . getObjectType ( ) . isInstance ( source ) ) ) { <END_BUG> GenericConversionService . logger . debug ( "No<seq2seq4repair_space>converter<seq2seq4repair_space>found<seq2seq4repair_space>-<seq2seq4repair_space>returning<seq2seq4repair_space>assignable<seq2seq4repair_space>source<seq2seq4repair_space>object<seq2seq4repair_space>as-is" ) ; return source ; } else { throw new org . springframework . core . convert . ConverterNotFoundException ( sourceType , targetType ) ; } } Object result = ConversionUtils . invokeConverter ( converter , source , sourceType , targetType ) ; if ( GenericConversionService . logger . isDebugEnabled ( ) ) { GenericConversionService . logger . debug ( ( "Converted<seq2seq4repair_space>to<seq2seq4repair_space>" + ( StylerUtils . style ( result ) ) ) ) ; } return result ; } public String toString ( ) { } protected Object convertNullSource ( TypeDescriptor sourceType , TypeDescriptor targetType ) { } protected GenericConverter getConverter ( TypeDescriptor sourceType , TypeDescriptor targetType ) { } protected GenericConverter getDefaultConverter ( TypeDescriptor sourceType , TypeDescriptor targetType ) { } private GenericConverter . ConvertiblePair getRequiredTypeInfo ( Object converter , Class < ? > genericIfc ) { } private GenericConversionService . MatchableConverters getMatchableConverters ( Class < ? > sourceType , Class < ? > targetType ) { } private void invalidateCache ( ) { } private Map < Class < ? > , GenericConversionService . MatchableConverters > getSourceConverterMap ( Class < ? > sourceType ) { } private void assertNotNull ( TypeDescriptor sourceType , TypeDescriptor targetType ) { } private GenericConverter findConverterForClassPair ( TypeDescriptor sourceType , TypeDescriptor targetType ) { } private Map < Class < ? > , GenericConversionService . MatchableConverters > getTargetConvertersForSource ( Class < ? > sourceType ) { } private GenericConverter getMatchingConverterForTarget ( TypeDescriptor sourceType , TypeDescriptor targetType , Map < Class < ? > , GenericConversionService . MatchableConverters > converters ) { } private void addInterfaceHierarchy ( Class < ? > ifc , LinkedList < Class < ? > > classQueue ) { } private GenericConverter matchConverter ( GenericConversionService . MatchableConverters matchable , TypeDescriptor sourceFieldType , TypeDescriptor targetFieldType ) { } @ SuppressWarnings ( "unchecked" ) private final class ConverterAdapter implements GenericConverter { private final ConvertiblePair typeInfo ; private final Converter converter ; public ConverterAdapter ( ConvertiblePair typeInfo , Converter < ? , ? > converter ) { } public Set < ConvertiblePair > getConvertibleTypes ( ) { } public Object convert ( Object source , TypeDescriptor sourceType , TypeDescriptor targetType ) { if ( source == null ) { return convertNullSource ( sourceType , targetType ) ; } return this . converter . convert ( source ) ; } public String toString ( ) { } } @ SuppressWarnings ( "unchecked" ) private final class ConverterFactoryAdapter implements GenericConverter { private final ConvertiblePair typeInfo ; private final ConverterFactory converterFactory ; public ConverterFactoryAdapter ( ConvertiblePair typeInfo , ConverterFactory < ? , ? > converterFactory ) { } public Set < ConvertiblePair > getConvertibleTypes ( ) { }

Fix:
if ( ( source == null ) || ( sourceType . isAssignableTo ( targetType ) ) ) {